There are various known techniques for discriminating between genuine items of currency and non-genuine items of currency. For the purposes of the disclosure an item of currency includes, but is not limited to, banknotes, valuable documents, checks, security documents, coins, tokens, coupons, or any other item of currency (genuine or non-genuine) used in exchange for goods and services.
The discrimination between genuine items of currency and non-genuine items of currency is often used in automated transaction devices. Automated transaction devices include, but are not limited to, Automated Teller Machines (e.g., ATMs), vending machines, automated kiosks, and gaming machines. In such devices, items of currency are inserted into the machine and are evaluated by a validation unit to determine genuineness. Inserted items of currency determined to be genuine are accepted into the machine (e.g., either permanently or temporarily) in exchange for goods or services. Items of currency inserted into the machine that are determined to be non-genuine can be rejected and returned to the user or held within the machine to prevent further circulation of the inserted non-genuine items of currency.
The validation unit evaluates inserted items of currency using known techniques such as optical response (e.g., reflectance and/or transmission in at least one wavelength), electromagnetic response (e.g., inductance or impedance), or physical dimension analysis (e.g., thickness, weight, or size). In the case of optical response, multiple locations of an inserted item of currency are evaluated relative to a known genuine item of currency to determine whether the inserted item is a genuine item of currency or a non-genuine item of currency. In other implementations, the multiple locations correspond to measurements of local electro-magnetic response of a coin item for example, especially when the coin is made of different materials such as bi-color coins. Typically the locations used for evaluating an inserted item of currency are selected manually by inspection of known genuine items of currency so that a high acceptance rate can be obtained while minimizing the acceptance of non-genuine items of currency. Often the manual selection process is performed by visual inspection. A limitation of such manual selection processes is that it is labor intensive and often expensive to determine which specific locations on a items of currency provide a good ability to discriminate genuine items of currency from non-genuine items of currency.